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The Identity String Field and the Tachyon Vacuum

Ian Ellwood·Bo Feng·Yang-Hui He·Nicolas Moeller
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Abstract

We show that the triviality of the entire cohomology of the new BRST operator Q around the tachyon vacuum is equivalent to the Q-exactness of the identity I of the star-algebra. We use level truncation to show that as the level is increased, the identity becomes more accurately Q-exact. We carry our computations up to level nine, where an accuracy of 3% is attained. Our work supports, under a new light, Sen's conjecture concerning the absence of open string degrees of freedom around the tachyon vacuum. As a by-product, a new and simple expression for I in terms of Virasoro operators is found.

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Ian Ellwood, Bo Feng, Yang-Hui He, Nicolas Moeller. 2001-06-14. The Identity String Field and the Tachyon Vacuum. https://doi.org/10.1088/1126-6708%2F2001%2F07%2F016

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